Daikin Perfera ARXM25A Service Manual page 61

Refrigerant piping repair
Refrigerant circuit vacuuming - general advice
RXM20~50A + ARXM25~50A + FTXM20~50A + ATXM20~50A + CTXM15A
Split Perfera ZETA R32
ESIE23-06 – 2023.12
CAUTION
Some outdoor units are equipped with a low pressure switch to protect the
compressor by switching it off. NEVER short‑circuit the low pressure switch during
pump down operation.
1 Remove the refrigerant connection cover, see Plate work.
2 Remove the cap from the stop valves.
3 Perform pump down operation, see installer reference guide for the correct
procedure.
4 After 5~10 minutes (after only 1~2 minutes in case temperature <–10°C),
close the liquid stop valve using a hexagonal wrench.
5 Check the manifold if vacuum is reached. Close the gas stop valve and stop
forced cooling operation.
▪ Make sure to cover open pipe ends during repair so no dust or moisture can
enter.
▪ Make sure to re‑apply insulation removed during repair.
▪ Pipe expansion / flare making:
- Remove any burrs on the cut surface using the correct tool such as reamer or
scraper (note that excessive deburring can thin the pipe walls and cause
cracking of the pipe).
- Make sure the flare has the correct size (use a flare gauge).
- Make sure no particles remain in the piping.
- Apply just a drop of refrigerant oil on the inner surface of the flare.
- Make sure the flare connection is tightened with the correct torque (torque
values refer to installation manual).
▪ Brazing:
- Use the correct brazing tool.
- Use a phosphor copper filler metal (silver composition of 0 to 2%). Do not use
flux material.
- Flush the piping before brazing with nitrogen to avoid oxidation of the inside of
the copper tubes (nitrogen purity ≥99.99%).
The effectiveness of the vacuum drying depends on many factors. Besides
following the correct procedures and using equipment that is well maintained, the
ambient conditions at which the vacuum is done MUST be considered. If there is
moisture in the refrigerant and the ambient temperature is lower, the vacuum
pressure that MUST be reached to allow the evaporation of the moisture will need
to be lower. In some cases the vacuum pump may NOT be able to achieve these
pressures. If possible, heat the locations where moisture is expected.
As a general target, the values below CAN be used as reference to achieve a proper
vacuum on the unit:
▪ Absolute pressure below 270 Pa MUST be reached. The time needed for the
pressure to lower is also depending on the moisture amount. If it takes very long
or it is hard to reach the pressure, this MIGHT be an indication of moisture
presence, so the vacuum pump will need to run longer.
4 | Third party components
draft – 21/12/2023 13:09
Service manual
61